The invention relates to a steering wheel with a decorative covering.
Steering wheels generally comprise a steering wheel frame with a steering wheel rim insert and spokes, which are sheathed in a layer of foam, for example of polyurethane. In addition, some steering wheels are provided with a decoration, for example with a wood decoration. For instance, DE 44 18 960 A1 discloses a covering part with a visible wood surface which has a load-bearing structural part consisting of dimensionally stable material which is connected to a covering forming the visible side. The load-bearing structural part, which preferably comprises two shell parts which can be placed one against the other, is fastened directly to the steering wheel rim insert. The latter has a substantially square cross section, to which the inner side of the load-bearing structural part is adapted. This cross section ensures that the load-bearing structural part cannot twist during fitting and consequently the decoration lies in the same place on every steering
The disadvantage is that, in the case of a steering wheel rim insert of a circular cross section, twisting of the load-bearing structural part is possible during fitting unless a device is used.
Apart from the square and circular cross sections mentioned of the steering wheel rim insert, other cross sections are also known. The load-bearing structural part must be adapted on its inner side to these respective cross sections.
This gives rise to the disadvantage that a special load-bearing structural part has to be provided in each case for different steering wheel rim inserts.
The invention is direct to being able to fit and design a load-bearing structural part, which is referred to below as the decorative covering part, in a manner which is secure with regard to twisting independently of the cross section of the steering wheel rim insert.
According to the invention, this is achieved by arrangement wherein, in the case of a steering wheel with decorative covering, a steering wheel frame with a steering wheel rim insert and spokes being sheathed in foam at least in certain sections and being provided with the decorative covering, in particular with a wood decoration. The steering wheel frame is provided in the regions intended for the decorative covering with a foam sheathing which has smaller outer dimensions than in the remaining regions which define sections which are uncovered by the decorative covering section. Fastened on this foam sheathing is at least one dimensionally stable decorative covering part, at least one centering means being provided between the foam sheathing and the covering part.
This construction of the steering wheel has the advantage that the outer contour of the cross section of the foam sheathing can remain the same, independently of the cross section of the steering wheel rim insert, so that the inner contour of the decorative covering part can likewise remain the same. Even if the foam sheathing has a circular cross section, twisting of the decorative covering part during fitting is not possible because of the centering means provided.
It is expedient that the foam sheathing has as a centering means in the region of at least one decorative covering part at least one round hole, which is assigned on the decorative covering part (5, 6) two crossing webs, the length of which corresponds to the diameter of the hole, so that the webs bear with their end faces against the wall of the-hole.
In one embodiment, two decorative covering parts reaching around the steering wheel rim are arranged in at least one region of the steering wheel and engage in one another at their contact surfaces. The decorative covering preferably comprises an upper half and a lower half. The upper half lies in its upper section against the foam sheathing and is provided there as the centering means. The lower half extends at a distance from the foam sheathing and is connected to the latter via at least one web.
The decorative covering parts preferably consist of dimensionally stable and temperature-resistant plastic. The decoration is expediently adhesively attached as a layer of veneer or film on the decorative covering parts. In other embodiments, a coating or a layer of metal is applied, for example, by electroplating, vapor depositing or flame spraying as decoration.
In one embodiment, the decorative covering is provided on the steering wheel rim in the region where the spokes adjoin and encloses the latter at least in certain sections.
In one embodiment, the decorative covering parts are expediently connected to the foam sheathing by adhesive bonding. In another embodiment, the decorative covering parts are adhesively bonded or welded to one another at their joins. In particular, the joins may be connected to one another by electromagnetic welding with thermoplastic welding filler. The electromagnetic welding takes place by means of process steps known per se.
While adhesives can act chemically on plastics, this risk does not arise in the case of welding. For these reasons, large gaps, which are necessary for tolerance reasons, can be filled by the filler.
For concealing the joins of the decorative connecting parts, a gap which has, for example, at least approximately a wedge-shaped cross section may be provided on the outer side of the decorative connecting parts.
In other embodiments, for concealing the joins a trim cord is in each case placed in the latter or the joins are covered by the decorative medium.